This disclosure relates in general to radio communication, and more specifically, without limitation, to two-way portable radio communication and time-division multiplexed communication. Two-way radios, generally referred in this application as simply radios, enable wireless communication between two or more people. To operate, many radios require either a push-to-talk (PTT) button or a voice operated switch (VOX). For example, walkie-talkies today require either a PTT button or VOX. One disadvantage of both PTT and VOX is that both PTT and VOX communications are half-duplex. In half-duplex communication, a radio can either transmit or receive at a given time, not both. In this application, the term PTT radio generally refers to radios using half-duplex communication where a user can either speak or listen at a given time, not both.
Full-duplex communication, commonly referred to as duplex communication, permits a radio to simultaneously transmit and receive at the same time, enabling a user of a duplex radio to both speak and listen at the same time. One way a radio can operate in a duplex mode, without needing a PTT button or VOX, is by using a base station. An example of wireless radios connected by a base station, and thus enabling full-duplex communication, is two users talking to each other using cell phones. Another example of wireless radios connected by a base station is a home telephone system with wireless telephones that can be placed in a conferencing mode.